1. Field of the Invention
The present invention is generally in the field of semiconductors. More particularly, the invention relates to the packaging of semiconductor dies.
2. Background Art
A power module having power devices can be used in high voltage and high current applications. The power module can include a half-bridge where the power devices are high side and low side devices that include, for example, an insulated-gate bipolar transistor (IGBT) or a power metal-oxide-semiconductor field-effect transistor (MOSFET) as a power switch. Each power switch can be provided on a respective die and is commonly in parallel with a diode, for example a freewheeling diode, which can be on the same or a different die than the power switch.
Although the power switch and the diode may be capable of high performance, performance of the power switch and the diode can be limited by how the dies are packaged. For example, electromagnetic interference (EMI) and parasitics are of great concern when connecting the dies in the power module. Furthermore, the power devices typically generate significant heat, which can degrade performance of the power switch and the diode if not sufficiently dissipated from the power devices.
One approach to packaging power devices in a power module is to connect high and low side devices that are arranged side by side on a substrate. Each of the high side and low side devices can have one or more die and conductive traces on the substrate that can be used as interconnects for the dies to form a half-bridge. However, using this approach, the conductive traces would likely require long routing paths on the substrate, and form undesirably asymmetric current paths with high parasitic inductivity and resistance. Also, as the substrate must accommodate the conductive traces and the dies, the substrate would be large and expensive. Thus, this approach would result in a power module having a large form factor and low power density. Furthermore, if bond wires were utilized to connect to the dies, it would be difficult to provide a heat sink to sufficiently dissipate heat from the high side and low side devices.
It would be desirable to provide power modules, with high side and low side devices, which are capable of overcoming the drawbacks and deficiencies described above.